Well packing apparatus



NOV. 28, 1967 YOUNG 7 3,354,963

WELL PACKI NG APPARATUS 3 Sheets-Sheet 1 Filed Nov 17, 1965 flay/d 5. young INVENTOR.

@ilwkk Nov. 28, 1967 D. E. YOUNG WELL PACKING, APPARATUS 5 Sheets-Sheet I5 7 Filed Nov 17, 1965 l N VEN TOR.

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United States Patent Ofilice 3,354,963 WELL PACKING APPARATUS David E. Young, Bellaire, Tex., assignor to Schlumberger Technology Corporation, Houston, Tom, a corporation of Texas Filed Nov. 17, 1965, Ser. No. 508,352 18 Claims. (Cl. 16612ll) This invention relates to apparatus for packing-off a well bore; and, more particularly, to packing apparatus which can be set in a well with a predetermined anchoring force and, once set, is responsive to pressure differentials acting from either direction in the well bore to develop, when needed, an increased anchoring force proportionately related to the acting pressure that is sufiicient to secure the apparatus in place.

In conducting such well-completed operations as acidizing, cementing, or fracturing, a full-opening well packer dependently coupled from a tubing string is positioned at a particular depth in a cased well and the packer set to isolate the formation interval to be treated from the remainder of the Well bore thereabove. Treating fluids are then pumped downwardly at high pressure through the tubing and packer and introduced into the formation being treated through perforations appropriately located in the casing.

In those instances where a well having several producing formations is being completed, a. selectively operable bridge plug is usualy dependently coupled beneath the full-opening packer. Such a bridge plug permits intervals of selected length to be packed-oil for selective treatment of different formation zones with only a single trip into the well. It will be appreciated that during the course of such completion operations, these packing apparatus are usually subjected to high fluid pressures acting alternately from both above and below them. Thus, these packers and bridge plugs must be firmly sealed and securely anchored against pressure differentials acting in either longitudinal direction.

Heretofore, extendible slip members have typically been employed to secure such packing apparatus from movement in at least one direction. Extendible anchoring members have also been developed which are hydraulically actuated by pressures acting from at least one direction for securing the apparatus against shifting in that direction. Such extendible members, however, typica-ly employ teeth that must be imbedded into the casing to secure the apparatus. Aside from damaging the casing, such toothed members are generally effective against movement in only one direction so that two oppositely directed sets are usually employed to prevent shifting of the apparatus in either direction. Moreover, once a toothed member is imbedded, it will be even more tightly imbedde-d by subsequent loads and, thereby, complicate its extrication as well as further damage the casing.

Accordingly, it is an object of the present invention to provide new and improved well-packing apparatus having a single wall-engagin anchor that is initially engaged with a predetermined anchoring force and, should a pressure differential develop that requires additional anchoring, will be pressed more tightly with a still greater force that is proportionately related to the pressure differential acting across the packer.

This and other objects of the present invention are obtained by providing packing apparatus with means for initially urging wall-engaging means against the casing with a predetermined force by applying Weight on the apparatus through the supporting tubing string and means for responding to a pressure differential across the apparatus otherwise suiilcient to shift it to further urge the wallengaging means with an increased anchoring force proportionately related to this differential.

3,3543% Patented Nov. 28, 1967 The novel features of the present invention are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation together with further objects and advantages thereof, may best be understood by way of illustration and example of an embodiment when taken in conjunction with the accompanying drawings, in which:

PK 1 is a view of a full-bore packer and a bridge plug employing principles of the present invention and depicted as they would appear within a well bore;

FIGS. 2A-2C are detailed, successive cross-sectional views of the bridge plug of FIG. 1;

FIG. 3 is a cross-sectional view taken along the lines 3-3 of FIG. 2B; and

FIGS. 4A4C are views similar to FIGS. 2A-2C but showing the bridge plug in its set position.

As seen in FIG. 1, a typical full-bore packer 10 is dependently connected from a tubing string 11 and positioned in a well bore 12 having a casing 13 set therein. An overshot 14 dependently connected beneath the well packer is releasably coupled over a fishing neck 15 on the upper end of a retrievable bridge plug 16.

Matched J-slots 17 (PEG. 2A) are arranged on opposite sides of the fishing neck 15 to cooperatively receive in wardly projecting lugs 18 on the overshot 14 whenever it is lowered over the fishing neck. After the lugs 18 have entered the open upper end of the long portions of the J-slots 17, the lugs are lockingly engaged in the closed short portion of the J-slots by a concerted application of counter-clockwise torque and a slight upward pull on the tubing string 11. Conversely, the overshot 14 is selectively disengaged from the fishing neck 15 by lowering the tubing string 11 slightly, torquing it to the right, and then pulling upwardly. By employing such a releasable coupling, the bridge plug 16 can be set at the lower limit of a particular formation interval and the packer 10 uncoupled and subsequently set thereabove irrespective of the length of the tubing sub 17 connecting them.

In general, the retrievable bridge plug 16 is comprised of a rotatable actuating mandrel 19 that is coupled to the fishing neck 15 and telescoped within a tubular housing 20 and arranged to be shifted therein bctwen an elevated position and a lowered position as respectively illustrated in FIGS. 2 and 4. Since those skilled in the art will recognize that such a well tool is typically comprised of separate tubular elements threadedly connected to one another to facilitate its manufacture and assembly, the drawings have been somewhat simplified by showing some of these separate elements as a single member for purposes of greater clarity.

As seen in FIG. 2, packing means, such as oppositely directed elastomeric packing cups 21 and 22 abutting elastomeric back-up rings 23 and 24, are mounted around the housing Eli and separated from one another by radially expansible anchor means 25 around the central portion of the housing. Means, such as conventional spring-biased rag blocks 26 around the housing 21 are arranged to frictionally secure the housing to the casing 13 with sulficient force to prevent movement of the housing as the mandrel 19 is manipulated but without unduly hampering positioning of the bridge plug 16 in the well bore 12.

it will be appreciated that when the bridge plug 16 is being shifted, for example, downwardly in a fluid-filled well, the downwardly facing lower packing cup 22 will expand outwardly against the casing wall to impede, if not totally prevent, downward movement of the bridge plug. To avoid such a problem, a central axial bore 27 is extended the full length of the mandrel 1? and capped at its upper end by the fishing neck 15. Radial ports 28 and 29 in the opposite ends of the mandrel 19 allow fluids to flow through the mandrel bore 27 and bypass the packing 3 cups 21 and 22 as the bridge plug 16 is being shifted within a well.

Fluid communication through the mandrel bore 27 is selectively controlled by an annular valve member 30 which is slidably disposed around the mandrel 19 immediately around the bypass ports and fluidly sealed thereto by O-rings 31 and 32 straddling the bypass ports 28. Lateral ports 33 are appropriately arranged in the slidable valve member 30 to be in register with the bypass ports 28 whenever the valve member is in the position illustrated in FIG. 2. The slidahle valve member 36 is arranged to be shifted longitudinally by the overshot 14 so that ports 28 and 33 are brought into register as the overshot is being engaged over the fishing neck (FIG. 2A) and the bypass ports are covered by the valve member as the overshot is being removed (FIG. 4A).

Whenever the overshot 14 is being removed, a group of dependent resilient fingers 34 spaced around the lower portion of the overshot have inwardly projecting shoulders 35 that engage a shoulder 36 on the sliding valve member 30 to pull it upwardly and close the bypass ports 28. As the valve member 30 is pulled upwardly, depending resilient fingers 3'7 around the lower end of the valve member are cammed outwardly as they pass over an annular shoulder 33 around the mandrel 19. After clearing the shoulder 38, the lower ends of these fingers 37 then engage the annular shoulder to hold the slidahle valve member 30 in its uppermost or port-closed position (FIG. 4A) after the overshot 14 has been removed. A shoulder 39 projecting inwardly from the central portion of the overshot 14 engages the valve member 36 and shifts it downwardly to its open position (FIG. 2A) whenever the overshot is coupled to the fishing neck 15.

Selectively operable latch means, such as an expansible split-nut 40 confined within an inwardly directed annular housing recess 41 and normally threadedly engaged with downwardly facing ratchet threads 52 around the mandrel 19, are provided to secure the mandrel in its elevated position (FIG. 2). Similarly, a second expansible splitnut 43 is confined within another housing recess 44 spaced below recess 41 and adapted to threadedly engage upwardly facing ratchet threads 45 around the mandrel 19 below the other threads 42 whenever the mandrel is shifted to its lowered position (FIG. 4).

By appropriately arranging these threads and nuts, clockwise rotation of the mandrel 19 will, for example, disengage the upper mandrel threads 42 from the upper nut 40 and, as the mandrel is shifted downwardly to its lowered position (FIG. 4), the lower mandrel threads 45 will ratchet into threaded engagement with the lower nut 43. Then, whenever it is desired to release the mandrel 19 and return it to its elevated position (FIG. 2), rotation in the same direction will disengage the mandrel threads 45 from the lower nut 43. As the mandrel 19 is returned upwardly, the upper mandrel threads 42 will ratchet into threaded engagement with the upper nut 4th to resecure the mandrel in its elevated position.

Thus, whenever the mandrel 19 is in its elevated position (FIG. 2), it cannot be shifted downwardly relative to the housing until it has been rotated to disengage the mandrel threads 42 from the upper nut 49. Similarly, whenever the mandrel 19 is in its lowered position (FIG. 4), it is restrained against upward movement relative to the housing 20 by the mandrel threads 45 and lower splitnut 43 until they are disengaged by rotation of the mandrel. It will be understood, of course, that the mandrel 19 can be manipulated only when the overshot 14 is coupled to the fishing neck 15.

The hydraulically actuated anchoring means mounted around the housing 20 are comprised of an expansible elastomeric sleeve 46 encircling the housing and a plurality of elongated all-engaging members 47 and 48 mounted longitudinally and uniformly spaced around the periphery of the sleeve. The enlarged upper and lower ends 49 and 50 of the elastomeric sleeve 46 are secured i by slidahle annular retainers 51 and 52 within opposed peripheral recesses 53 and 54 around the housing 20. O-rings 55 and 56 around the retainers 51 and 52 fluidly seal the sleeve ends 49 and 59 within the recesses 53 and 54 to provide a fluid-tight space 57 between the sleeve 46 and housing 20.

Each of the casing-engaging members 47 and 48 is elongated and has a thick, arcuate cross-section (FIG. 3). Alternate ones 47 of the casing-engaging members are centrally aligned and mounted on the outer convex surface of relatively thin, elongated, arcuate backing members 58. A suflicient number of these mounted members 47 are disposed around the periphery of the elastomeric sleeve 46 that the backing members 58 substantially encompass the sleeve. The remaining casing-engaging members .8 are unmounted and alternately disposed between the mounted casing-engaging members 47 in such a manner that the unmounted members 48 straddle adjacent backing members 58 and cover the gaps 59 therebetween.

The ends of the casing-engaging members 47 and 48 are beveled, as at 60 (FIG. 2), for reception within the opposed annular housing recesses 53 and 54. It will be appreciated, therefore, that although the casing-engaging members 47 and 48 will be moved radially outwardly whenever the elastomeric sleeve 46 is inflated, the beveled ends of the members cannot escape from the housing recesses 53 and 54.

Turning now to the hydraulic actuating system for the anchoring means 25, the fluid-tight space 57 between the elastomeric sleeve 46 and housing 20 is connected, by way of a plurality of lateral ports 61 through the housing 20, to the annular clearance space 62 between the housing and mandrel 19. This annular clearance space 62 is isolated above and below the anchoring means 25 by O-rings 63 and 64 respectively.

The annular clearance space 62 is enlarged, as at 65, above the elastomeric sleeve 46 and receives an insert sleeve '66 fluidly sealed by spaced O-rings 67 and 68 to the housing 20 to provide an annular chamber 69 around the mandrel 19 in which an annular piston 70 is slidably disposed. To fluidly seal the piston 70 within the chamber 69, O-rings 71 and 72 are longitudinally spaced around the piston and fluidly sealed to the insert 66, with another O-ring 73 being mounted within the piston and fluidly sealed to the mandrel 19. A lateral port 74 through the housing 20 between O-rings 67 and 68 and insert sleeve 66 below piston 70 provides fluid communication into the piston chamber 69 from the exterior of the bridge plug 16 between the packing cups 21 and 22. Thus, so long as the piston 70 remains in the position illustrated in FIG. 2, the fluid-tight space 57, the clearance space 62 and piston chamber 69 are open through the port 74 to the exterior of the bridge plug 16 between the packing cups 21 and 22.

It will also be appreciated that when the bridge plug 16 is being shifted in a fluid-filled well, a pressure differential will develop between and the fluids trapped in the annular space around the housing 20 between the packing cups the fluids in the well above and below the packing cups 21 and 22. Such a pressure differential will expand the cups 21 and 22 against the casing wall, which action can damage the packing cups as the bridge plug 16 is being positioned in the well.

To eliminate this action, a lateral port 75 is provided through the housing 20 below the upper packing cup 21 and above the piston it! and into the enlarged clearance space 65 immediately above the piston. Another port 76 is provided in the mandrel 19 so that when the mandrel is in its elevated position (FIG. 2), there is fluid communication between the central mandrel bore 27 and the exterior of the bridge plug 16 intermediate of the packing cups 21 and 22. Thus, so long as this fluid communication exists, the fluid pressure intermediate of the packing cups 221 and 22 will always be substantially equal to the presa sure in the well above and below the packing cups. To close-off this communication, an inwardly directed sealing member 77 disposed within the engaged bore 65 immediately below the port 75 is arranged to sealingly engage an enlarged portion 78 of the mandrel 19 whenever the mandrel moves downwardly a short distance. Thus, it will be seen from comparison of FIGS. 2 and 4 that as the mandrel 19 is shifted toward its lowered position, the sealing member 77 will be fluidly sealed around the enlarged mandrel portion 78 to close the chamber 69 above piston 70 and block fluid communication through the outer port 75.

As the mandrel 19 is further shifted toward its lowered position (FIG. 4), a shoulder, such as the lower face 79 of the enlarged mandrel portion 78, is appropriately spaced above the piston 70 to cooperatively engage the piston and move it downwardly after the outer port 75 has been closed. It will be noted that as soon as the piston 70 has moved downwardly only a short distance, the O- ring 72 will be below port 74 and trap whatever liquids there are below the piston in the piston chamber 69, clearance space 62 and fluid-tight space 57. Thus, as the mandrel 19 and piston 70 are moved further downwardly, hydraulic pressure will be developed in these closed spaces 69, 62 and 57 to expand the expansible sleeve 46 and urge the casing-engaging members 47 and 48 outwardly against the adjacent casing wall.

Accordingly, once the mandrel 19 has reached its lowered position (FIG. 4), the lower mandrel threads 45 will be co-engaged with the lower split-nut 43 to hold the mandrel in this position. The mandrel shoulder 79 will be abutted on top of the piston 70 to hold it 'in its lower position. Thus, so long as the mandrel threads 45 remain engaged, neither the mandrel 19 'nor piston 70 can shaft upwardly.

To restore the mandrel 19 and piston 70 to their original positions, the mandrel threads 45 must be disengaged from the lower nut 43. By rotating the mandrel 19 as previously explained, the mandrel is released and can be returned to its elevated position (FIG. 2). As the mandrel 19 returns to this position, a shoulder 80 thereon below the piston 70 engages the piston and carries it upwardly to its initial position (FIG. 2B). As the piston 70 shifts upwardly, the port 74 is first uncovered to relieve the hydraulic pressure maintaining the casing-engaging members 47 and 48 in their extended position. Then, as the mandrel 19 moves further upwardly, the enlarged mandrel portion 78 clears the sealing member 77 to again open the outer port 75 into communication with the piston chamber 69 and port 76. The upper mandrel threads 42 'will then ratchet into engagement with the upper split-nut 40 and again resecure the mandrel 19.

Turning now to the operation of the bridge plug 16. As seen in FIG. 2, when the bridge plug 16 is being positioned in the well bore 12 (FIG. 1), it will be appreciated that the hydrostatic pressure will force liquids in the well, such as drilling mud and the like, into the piston chamber 69 by wa of port 74 and port 75. Inasmuch as the fluid-tight space 57 and clearance space 62 as well as the piston chamber 69 above and below the piston are initially at atmospheric pressure, these spaces will be rapidly filled with the liquids in the well. The inner' wall of the insert sleeve 66 is recessed, therefore, as at 81, adjacent the upper piston O-ring 71 to prevent trapping of atmospheric pressure between the O-rings 71 and 72 which otherwise might impede travel of the piston 70. Once the piston 70 moves downwardly, however, the O- ring 71 will come into sealing engagement with the insert 66.

Whenever the bridge plug 16 has been positioned at a desired depth in the well, the tubing string 11 is slackedoff slightly and slowly rotated in a clockwise direction. This action disengages the mandrel threads 42 from the upper split'nut 40 to permit the mandrel 19 to shift downwardly relative to the housing 2.0 which is frictionally d secured to the casing 13 by drag blocks 26. Once the mandrel 19 is released from the upper split-nut 40, it is free to shift further downwardly to first bring the enlarged mandrel portion 78 into sealing engagement with the sealing member 77 and then shift the piston 70 downwardly once the shoulder 79 has engaged the piston. As the piston 76 is shifted downwardly, the O-ring 72 thereon seals the port 74 to isolate the liquids that are trapped therebelow.

Downward movement of the piston 70 will, of course, develop a hydraulic pressure in that portion of the nowsealed hydraulic system comprised of the piston chamber 69, annular clearance 62 and fluid-tight space 5'7 to indate the elastomeric sleeve 46. This hydraulic pressure that is developed will, of course, be proportionately related to the downward force applied to the mandrel 19. Thus, by observation of the weight indicator (not shown) that is typically used at the surface to measure the upward pull required to support the string of tubing and tools in the well bore at any given moment, it will be possible to slack-off a particular magnitude of weight on the tubing string 11 to develop a corresponding predetermined pressure in the hydraulic system for frictionally engaging the wall-engaging members 47 and 48 against the casing 13 with predetermined force. This predetermined force is, of course, selected in accordance with the anticipated well conditions.

Once the mandrel 19 has traveled a sufiicient distance downwardly, the lower mandrel threads 45 will ratchet freely downwardly through the lower split-nut 43 until the tubing string 11 is halted by the increased hydraulic pressure developed by the piston 70. Once the tubing string 11 is halted, the mandrel 19 will, of course, be prevented from returning upwardly by the co-engagement of the lower mandrel threads 45 and lower split-nut 43.

Once the mandrel 19 has reached the position shown in FIG. 4, the tubing string 11 is picked up to remove the overshot 14 from the fishing neck 15. As the overshot 14 is removed, the valve member 30 is moved upwardly by the depending fingers 34 so as to block fluid communication through the mandrel bore 27 and port 28. Once the valve member 30 is closed, the bridge plug 16 is securely anchored against the casing 13 and capable of holding a pressure differential acting in either direction from above or below the bridge plug.

Assuming, for example, that the pressure in the well bore 12 below the bridge plug 16 is greater than that above, this greater pressure will be admitted through the mandrel port 76 into the upper portion of the piston chamber 69. It will be recognized, however, that this pressure in the well will not be efiective to move the piston 70 further downwardly until it exceeds the hydraulic pressure developed upon setting of the bridge plug 16.

Thus, by initially setting sufficient weight on the bridge plug 16 to anchor it against a predetermined pressure differential, it will not be necessary to develop a further anchoring force until this pressure diiferential is exceeded. Should, however, this occur, an increased pressure from below the bridge plug 16 will be admited through port 76 above the piston 70 to urge the piston further downwardly and develop 'an increased hydraulic pressure and corresponding increased anchoring force. The mandrel 19 will, however, be still secured by the split-nut 43 as the piston 70 shifts away from shoulder 79. Should this increased pressure be reduced, the piston 70 will return upwardly and, as the pressure decreases, eventually re-engage the shoulder 79 to reduce the hydraulic pressure to its original magnitude.

Should, perch-ance, there be a greater pressure above the bridge plug 16 than that below, the mandrel 19 will be urged further downwardly since the lower mandrel 45 threads can ratchet further downwardly through the lower nut 43. Hereagain, however, the mandrel 19 can not move downwardly until the pressure forces acting on the mandrel exceed those acting upwardly thereon from the piston 70 to shoulder 79. Thus, before-the initially developed hydraulic pressure becomes inadequate to secure the bridge plug 16, the pressure differential otherwise tending to shift the bridge plug 16 downwardly will be effective to develop a still greater anchoring force. It should be noted that in such an event, the mandrel 19 and piston 70 will not subsequently return to their initial positions upon decrease of the well pressure it the higher pressure was suificient to ratchet mandrel threads 45 into engagement with one or more still lower threads in the lower split-nut 43. This poses no particular problem since the bridge plug 1 6 will only be held with a greater anchoring force until released.

It should also be understood that by placing the anchor means between the spaced packing cups 21 and 22, the anchor means is more elfective. For example, with a greater pressure below the bridge plug 16 than that above, the hydrostatic pressure acting inwardly against the elastomeric sleeve 46 is substantially equal to the lower pressure above the bridge plug 16 since the upper packing cup 21 will be contracted to equalize any pressure dilferential in that direction. The lower packing cup 22 will, of course, be effective to pack-off against such a pressure ditferential. The reverse situation will also occur whenever the pressure differential is acting from above the bridge plug 16. Thus, irrespective of the direction of the pressure difierential, the higher well pressure will be acting to develop a hydraulic pressure which will always be opposed only by the lower pressure around the elastomeric sleeve 46 and between the packing cups 21 and 22.

Accordingly, it will be appreciated that the casing-engaging members 47 and 48 will be held against the casing 13 with a force that is directly related to the hydraulic pressure initially developed upon setting of the bridge plug 16. Thereafter, any pressure differential that is greater than the differential between the developed hydraulic pressure and that of well fluids around the anchor 25 will further secure the casing-engaging members 47 and 48 with an additional force that is proportionately related to the pressure differential across the bridge plug 16.

To retrieve the bridge plug 16, it is necessary only to re-engage the overshot 14 over the fishing neck 15. As the overshot 14 is being lowered over the fishing neck 15, the depending fingers 34 on the overshot will engage the upper end of the slidable valve member to shift it downwardly to its initial position. Once the valve member 30 is shifted downwardly sufficiently to again bring ports 28 and 33 into register, pressure will be equalized across the bridge plug 16. Then, by picking-up and rotating the tubing string 11 in a clockwise direction, the lower mandrel threads will be threadedly disengaged from the lower split-nut 43. Once these threads 45 have been so disengaged, the mandrel 19 is again free and can be pulled upwardly by the tubing string 11. As the mandrel 19 shifts upwardly, the upper mandrel threads 42 will ratchet upwardly through the upper split-nut 40 to again secure the mandrel 19 in its uppermost position (FIG. 2). As the mandrel 19 returns upwardly, the shoulder 8% below the piston '70 will engage the bottom of the piston and carry it upwardly to its initial position thereby again opening port 74 to release the hydraulic pressure developed in the piston chamber 69. Also, as the mandrel 19 moves upwardly, the enlarged mandrel portion 78 will be disengaged from sealing member 77 and again open communication through ports 75 and 76 to equalize pressure across the piston 79 and packing cups 21 and 22. With the mandrel 19 again restored to its elevated position as illustrated in FIG. 2, the bridge plug 16 can then be retrieved.

Accordingly, it will be appreciated that the present invention provides a new and improved packing apparatus that can be securely anchored in 'a well against pressure diflerentials acting in either direction. By setting the packing apparatus with a predetermined force, the packing apparatus will remain fixed against anticipated Well pressure differentials. Should these differentials increase, however, means are provided whereby further anchoring forces will be developed as required to maintain the packing apparatus in position.

While a particular embodiment of the present invention has been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects; and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

I claim:

1. A well tool sized and adapted for reception in a well bore comprising: a housing; normally-retracted pressureresponsive means on said housing adapted for extension against a wall in a well bore in response to an actuating pressure; a body movably disposed in said housing, said body being adapted for releasable connection to a suspension member and movable thereby relative to said housing from a normal position to successively-advanced displaced positions; means on said housing for securing said body against return from said displaced positions to said normal position; mean responsive to movement of said body to said displaced positions for developing an actuating pressure to extend said normally-retracted means against a well bore wall with a force proportionately related to the force applied to said body by a suspension member; and means responsive to pressure differentials between fluids in a well bore above and below said well tool for developing a greater actuating pressure to urge said normally-retracted means against the Well bore wall with an increased force proportionately related to such a pressure differential.

2. The well tool of claim 1 wherein said pressuredeveloping means includes means defining an enclosed liquid-receiving space in said housing in fluid communication with said normally-retracted means, piston means in said enclosed space, and means on said body for shifting said piston means into said enclosed space to develop said actuating pressure as said body is moved away from said normal position.

3. The well tool of claim 2 wherein said pressureditferential responsive means includes passage means communicating well bore fluid pressures to said piston means for shifting said piston means further into said enclosed space.

4. The well tool of claim 2 wherein said securing means is selectively releasable to return said body to said normal position in response to a predetermined manipulation of a suspension member connected to said body and said piston-shitting means are spaced first and second opposed shoulders on said body adjacent opposed portions of said piston means and respectively adapted to engage and shift said piston means into and out of said enclosed space.

5. The well tool of claim 4 wherein said pressure-differential responsive means includes passage means communicating well bore fluid pressures to said piston means for shifting said piston means further into said enclosed space.

6. The well tool of claim 2 further including passage means in said housing for admitting liquids from a well bore into said enclosed space and means responsive to movement of said body away from said normal position for fluidly sealing said passage means.

7. The well tool of claim 6 wherein said pressure-differential responsive means includes second passage means communicating well bore fluid pressures to said piston means for shifting said piston means further into said enclosed space.

8. A well packer sized and adapted for packing-01f a well bore comprising: a tubular housing; normally-retracted pressure-responsive anchoring means on said housing adapted for extension against a wall in a well bore in response to an actuating pressure to secure said housing relative to the wall; packing means on said well packer; a body movably disposed in said housing, said body being adapted for releasable connection to a suspension member and longitudinally movable thereby in one direction relative to said housing from a normal position to successively-advanced longitudinally-displaced positions; means on said housing and body for securing said body against return from said displaced positions to said normal position; means in said housing responsive to movement of said body to said displaced positions for developing an actuating pressure to extend said anchoring means against a well bore wall with an anchoring force proportionately related to the force applied to said body by a suspension member, said anchoring force being sufficient to secure said well packer against shifting in a well bore from pressure differentials between fluids therein above and below said well packer up to a particular magnitude; and means responsive to greater pressure differentials between such fluids for developing nronortonately greater actuating pressures to urge said anchoring means against the well bore wall with an increased anchoring force proportionately related to the greater pressure difierential.

9. The well packer of claim 8 wherein said pressuredeveloping means includes means defining an enclosed liquid-receiving space in said housing in fluid communication with said anchoring means, piston means in said enclosed space, and means on said body for shifting said piston means into said enclosed space to develop said actuating pressure as said body is moved in said one direction.

10. The well packer of claim 9 wherein said packing means includes first and second oppositely directed packing cups around said housing above and below said anchoring means, and further including normally-open valve means providing fluid communication from between said packing cups to the well bore above and below said well packer, said valve means being closed in response to movement of said body in said one direction.

11. The well packer of claim 10 wherein said securing means is selectively releasable to return said body in the opposite direction to said normal position in response to a predetermined manipulation of a suspension member connected to said body and said piston-shifting means are longitudinally-spaced first and second opposed shoulders on said body above and below opposed portions of said piston means and respectively adapted to engage and shift said piston means in said directions.

12. The well packer of claim 10 wherein said pressuredifferential responsive means includes passage means communicating well bore fluid pressures tending to move said body in the opposite direction into said enclosed space for shifting said piston in said one direction to develop said increased anchoring force.

13. The well packer of claim 12 further including sec- 55 ond passage means in said housing for admitting liquids from a well bore into said enclosed space and means responsive to movement of said body in said one direction for fluidly sealing said second passage means.

14. The well packer of claim 13 wherein said securing means is selectively releasable to return said body in said opposite direction to said normal position in response to a predetermined manipulation of a suspension member connected to said body and said piston-shifting means are longitudinally-spaced first and second opposed shoulders on said body above and below opposed portions of said piston means and respectively adapted to engage and shift said piston means in said directions.

15. A Well tool sized and adapted for reception in a well bore comprising; rst and second telescoping members movable relative to one another between spaced positions; pressure-responsive anchor means on said first member adapted for anchoring said well tool in a well bore in response to an actuating pressure; a pressure chamber coupled to said anchor means and including a movable piston between said members; means responsive to movement of said second member toward one of said spaced positions moving said piston for developing a pressure in said chamber to actuating said anchor means; means releasably securing said members against return to the other of said positions but allowing further movement of said second member toward said one position; and means permitting application of well bore pressure to said piston for further movement thereof independently of said second member to develop additional pressure in said chamber.

16. The well tool of claim 15 further including packing means on said first member, passage means in said first member for admitting liquids from a well bore into said pressure chamber; and means responsive to movement of said second member toward said second position for fluidly sealing said passage means.

17. The well tool of claim 16 wherein said pressure application means includes second passage means in one of said members for communicating well bore pressure to said piston.

18. The well tool of claim 17 wherein said packing means includes first and second oppositely directed packing cups around said first member above and below said anchor means, and further including normally-open valve means providing fluid communication from between said packing cups to the well bore above and below said well tool, said valve means being closed in response to movement of said second member toward said second position.

References Cited UNITED STATES PATENTS 2,638,168 5/1953 Parks 166-120 2,990,882 7/1961 Brown 166-121 X 3,195,642 7/1965 Conrad 166120 X 3,288,219 11/1966 Young et a1. 166-120 3,305,021 2/1967 Lebourg 166122 CHARLES E. OCONNELL, Primary Examiner. DAVID H. BROWN, Examiner. 

15. A WELL TOOL SIZED AND ADAPTED FOR RECEPTION IN A WELL BORE COMPRISING; FIRST AND SECOND TELESCOPING MEMBERS MOVABLE RELATIVE TO ONE ANOTHER BETWEEN SPACED POSITIONS; PRESSURE-RESPONSIVE ANCHOR MEANS ON SAID FIRST MEMBER ADAPTED FOR ANCHORING SAID WELL TOOL IN A WELL BORE IN RESPONSE TO AN ACTUATING PRESSURE; A PRESSURE CHAMBAER COUPLED TO SAID ANCHOR MEANS AND INCLUDING A MOVABLE PISTON BETWEEN SAID MEMBERS; MEANS RESPONSIVE TO MOVEMENT OF SAID SECOND MEMBER TOWARD ONE OF SAID SPACED POSITIONS MOVING SAID PISTON FOR DEVELOPING A PRESSURE IN SAID CHAMBER TO ACTUATING SAID ANCHOR MEANS; MEANS RELEASABLY SECURING SAID MEMBERS AGAINST RETURN TO THE OTHER OF SAID POSITIONS BUT ALLOWING FURTHER MOVEMENT OF SAID SECOND MEMBER TOWARD SAID ONE POSITION; AND MEANS PERMITTING APPLICATION OF WELL BORE PRESSURE TO SAID PISTON FOR FURTHER MOVEMENT THEREOF INDEPENDENTLY OF SAID SECOND MEMBER TO DEVELOP ADDITIONAL PRESSURE IN SAID CHAMBER. 